This invention pertains to an automated thread tapping machine. More particularly, this invention pertains to a bent shank thread tapping machine having a reciprocating tapping head.
Thread tapping machines are well-known in the art. These machines are used to, for example, tap or form female threads in articles, such as fasteners, for example, nuts. In one known thread tapping machine, a bent shank having a cutting tool (i.e., a tap flute) formed at the head thereof is positioned in a stationary tapping head. An article into which threads are to be tapped is moved into engagement with the tap flute at the end of the shank. The article is further urged into engagement with the cutting tool and threads are cut or tapped into the article. The article is then urged along the shank (at a portion of the shank having a reduced diameter) and is discharged from the shank after the bent portion thereof.
Another type of thread tapping machine includes a head portion having a tap flute mounted thereto. The head reciprocates so as to bring the cutting tool into contact with an article into which threads are tapped. The head then retracts after the threads have been cut.
Although both of these known machines are quite useful for their intended purposes, there are drawbacks. First, with respect to the bent shanktype machine, the articles into which the threads are tapped must be moved into contact with the rotating shank. In that the article may be quite small or conversely quite large, it can be difficult to support and maintain these articles relatively rigidly as they are moved into contact with the rotating shank. With respect to the reciprocating-type machine, the process of moving the head into contact with the article and then withdrawing the head is time consuming, and is quite labor intensive. In addition, the thread cuts can be compromised by xe2x80x9cbacking-outxe2x80x9d the cutting tool after the threads have been cut.
Accordingly, there exists a need for an automated tapping machine that can tap threads into articles a relatively continuous basis. Desirably, such a machine can tap threads into a wide variety of articles of different sizes and can do so quickly and in a cost efficient and effective manner.
A thread tapping machine taps female threads into a series of associated articles that are held in an associated stationary fixture or frame. The tapping machine includes a head having a housing that is mounted for reciprocating movement toward and away from the stationary fixture. The housing is rotationally fixed.
A spindle is carried by the housing for reciprocating movement along with the housing and for rotational movement within the housing. One or more bearings can be used to mount the spindle within the housing.
A shank is carried by the spindle for rotational and reciprocal movement with the spindle. The shank has a flute tap section having a largest diameter and an elongated shank body having diameter smaller than the flute tap section diameter. The shank further includes a transverse section opposite the flute tap and a bent section between the transverse section and the elongated body.
A first drive moves the housing in a reciprocating manner. In a current embodiment, the first drive is an air cylinder. A second drive moves the spindle in a rotational manner. In a current embodiment, the second drive is an electric drive, i.e., an electric motor.
The housing is moved toward and into contact with a first of the series of articles with the spindle rotating so that the flute tap section engages the first article to form a thread therein. When the first article is released from the fixture, in conjunction with the housing reciprocating away from the fixture, the article is urged along the shank, away from the flute tap section to and around the bent shank. The first article is eventually ejected from the shank at the transverse section.
In a preferred embodiment, a spindle tube is disposed coaxially within the spindle, with the shank disposed within the spindle tube. An opening can be formed in a side wall of the spindle, through which the shank transverse portion extends. In this manner, the shank rotates with rotation of the spindle.
The housing can include a receiving region for receiving the articles ejected from the shank transverse section. To provide interconnection of the second drive and the spindle, the housing can include a longitudinal opening and the machine can include a drive dog extending from the second drive to the spindle through the longitudinal opening.
Preferably, the spindle tube includes an interference member, such as a detent that is configured to permit the articles to pass forwardly along the shank from the flute tap to the bent section and is further configured to prevent the articles from passing rearwardly along the shank from the bent section to the flute tap.
The detent can be disposed in an opening formed in the spindle tube. In a present embodiment, the detent is formed from spring steel.
These and other features and advantages of the present invention will be apparent from the following detailed description, in conjunction with the appended claims.